1. Field of Invention
The invention relates to a WLAN (wireless local area network) and, in particular, to a method of a tuning process of WLAN devices.
2. Related Art
Accompanying with the development of wireless transmission industry, various kinds of devices and technologies applied to multiple frequency transmission are invented. The WLAN device utilizes multiple frequency channels for receiving or transmitting signals. Unfortunately, the variants between the receiving system and the transmitting system having radio and analog modules of different components cause the different channel characteristics. To identify the characteristics of the multiple frequency channels and to eliminate the distortion of the received or transmitted signals, the tuning process for the WLAN device must test the channels and generate the optimum parameter(s) for setting. The WLAN device has various kinds of parameter observations and parameter settings such as the error vector magnitudes (EVM) or the sidelobe levels of the measured signals for tuning the transmit-powers of different channels, or the packet error rate (PER) of the measured signals for tuning the receive-powers of different channels. Regarding to the device utilizing IEEE 802.11 (WLAN/WiFi), IEEE 802.16 (may be named as WMAN/WiMAX), IEEE 802.15.3a (WPAN/UWB), or IEEE 802.20 (WWAN/MBWA), both the architectures of multiple frequency channels in a single antenna/radio and in multiple antennas/radios (MIMO or Multiple-Input-and-Multiple-Output systems as per IEEE 802.11n and other related standards) must to test and to tune the different channels or the different antennas/radios so as to ensure the production yield of the WLAN devices.
In the early days, the WLAN devices are tuned one by one. In more detailed, the channels of each WLAN device are tested and tuned by turn. According to the progress of the related technologies, the customers have more and more requirements and the environment for wireless transmission becomes more complex. In the complex environment for wireless transmission, the WLAN devices must have more usable channels, which results in that to tune the WLAN devices one by one takes longer testing time. In other words, since the channels of the WLAN device are increased and the tuning speed for a single channel is the same, the production time for the WLAN devices grows. To speed the tuning process for the WLAN devices, the tuning process with the normalized settings is adopted. In this case, some channels of several WLAN devices are tested to tune the transmit-power and receive-power to reach the minimum EVM, minimum sidelobe levels, or minimum PER so as to obtain the parameter setting values for most channels of most WLAN devices. Alternatively, to reduce the testing time, the parameters obtained in the product developing stage can be used as the parameter setting values in the mass production stage.
As mentioned above, the tuning process with the normalized settings can shorten the testing time of the WLAN devices. However, this method uses the only normalized setting for each parameter setting, so that the identification of the multiple frequency channels may not be maintained and the distortion in receiving signals or transmitting signals may not be eliminated. To consider with the testing speed and the device quality both, the tuning process by utilizing means or arithmetic means are disclosed. In this method, a front channel, a middle channel and a rear channel are tested. For all channels between the front channel and the middle channel, the median or the average of the parameters for the front and middle channels is used as the parameter calibration value for tuning all of the channels between the front and middle channels or for tuning the arithmetic mean channels. Similarly, for all channels between the middle channel and the rear channel, the median or the average of the parameters for the middle and rear channels is used as the parameter calibration value for tuning all of the channels between the middle and rear channels or for tuning the arithmetic mean channels. Regarding to the current situation in Taiwan, the WLAN (in the case of IEEE802.11b/g) devices use channels 1 to 11. In this case, the tuning process by utilizing means or arithmetic means is to obtain the parameters of channel 1, channel 6 and channel 11 in advance. Then, the average of the parameters of channels 1 and 6 is calculated to be the parameter of channel 3 or channel 4 or to be the parameters of channels 2 to 5. As the same manner, the average of the parameters of channels 6 and 11 is calculated to be the parameter of channel 8 or channel 9 or to be the parameters of channels 7 to 10. The tuning process by utilizing means or arithmetic means is to test some predetermined channels in each WLAN device. In other words, this method uses only two or three parameters to determine the parameter calibration value for all channels of a single WLAN device. However, regarding to the WLAN devices, the improvement of the quality for each channel is limited.
It is therefore an important subject of the invention to provide a method of a tuning process for WLAN devices, which can tune multiple frequency channels efficiently and accurately, improve the transmit maximum power or more while decreasing the EVM and sidelobe levels, and enhance the receive sensibility while decreasing the PER